Camera bearing in apparatus for photogrammetrically plotting oblique photographs taken from aircraft



May 4, 19

37. o. voN @RUBI-:R

Filed Nov. 18, 1936 {Wmww Patented May '4, 1937 -"1unfrei).A s'r-Arr-:s PATENT oFFicE v t. I CAMERA nEAnuvigsrrAnA'rUs rolt PHOTOGRAMHETRICALLY PLOTTIN G OBLIQUE PHOTOGRAPHS TAKEN FROM AIRCRAF'1\` Otto von Gruber, Jena, Germany, assignor to the ilrm Carl Zeiss, Jena, Germany The invention concerns a bearing fora camera projecting an image on a plane of projection in apparatus which work4`v on'the principle' of double projection andare used forv photogram- 5 inetricallyl plotting image plates exposed on aircraft obliquely at a definite angle a' to the horizontal plane, the bearing havinga three-dimensional system of cross-slides which supports by means of a Cardan link a bearing body Von which the camera is mounted in such a manner that this camera is Yrotatable about an axis contain' ying the optical'centrefof the camera objective, that this optical' centre coincideswith the centre of theCardan link, and that the axis of "rotation of the* camera intersects the interior axis 'of rotation of theCardan ylink at right angles.

To ensure`in' such apparatus a simplified orientation of the images, the invention provides `a Acamera bearing permitting inclination of the 20 image plate' of the camera to vtheaxisfoffrotation W'W `oi the camera at an angle s in such a manner that this plate is intersectedby the axis W-W at a point'lying asn'ealth Plate plumb point as possible, that the objective and the image plate are'so positioned relatively to each other as to make the principal plane yH----H of the objective pass through the line in which the emulsion side S-S of 'the image plate intersects the projection plane P--P at a medial distance of this plane P-P from the objective,

and that the exterior axis of rotation of U-U. of

the Cardan link is .inclined to the projection surface P-P at an angle y equal to the sum of the said two angles a and 13 less 90.

The reasons for the said construction of the camera mounting providing a simpliiled orientation of the images are the following: It is a well known fact that, in radial triangulation, points near the plat'e plumb line are especially insensitive to errors of orientation when directions of lines are to be determined which'connect these points 'to any other points. Hence, it is is expedient to so position the orientation parts of the projection camera that, when theorienta-v tion is changed, the displacements of the projections of such points on the projection surface are as few and as unequivocal as possible, which is the aim of the invention.

The new camera bearing acts in. such a maner that the -projection on the plane of projection P-P of the point lying in the' axis of rotation W-W of the camera remainscompletely motionless when the camera is rotated` about the said axis W--W, that the projection of this point is displaced along a line parallel to the 1 Claim. '(Cl. 33-20) interior axis oiroiaiion -v-v of the cardan link when the camera is vrotated about the ex- .terior axis of rotation U--U of the Cardan link,

and that the projection of this point is displaced at right angles to" the line parallel to the interior axis V -V when the camera is rotated about this axis V-V. .In the accompanying drawing, which illustrates the invention and represents a projection camera and its mounting, Figure 1 shows the camera in elevation, Figure 2 is a partial p lan view. of the camera mounting, and Figure 3 shows the camera mounting in a section through the dash-line in Figure 1.

I is a lrod of the plottingapparatus of which v the projection camera .forms part. The rod. I

is provided lengthwise-with a rack 2 and a knifeedge 3. The knife-edge 3 supports@ camera holder ltraversed by ashaft 5 which is connected. tol a toothed wheel 6 in mesh with` the rack 2.y `By `means oi? la. milled vhead 1.1,. the 4 toothed wheelf.I can be so rotated as toidisplace 8. of the holder 4. ina direction Y--Y at right displacements of the slide 9 relative to the holder 4 being effected byfmeansrof'a milled head1!) and a threaded spindle II whose axis coincidesv with the direction of displacement Y-Y and which is 'in mesh with the thread of a nut piece I2 of the holder. 4. On the slide '9 is mounted a slide I3- displaceable in a directionZ-Z at right angles to the directions of displacement X-X and Y-Y. On the slide I 3 is rotatably mounted a threaded spindle Il whose axis coincides with the direction of displacement Z-Z and which engages in the thread of a. nut piece I5 of the slide 9. Rotating the spindle Il by means of a milled head I6 entails a displacement of the slide I3 relative to the slide 9. The

.ho1der`ilonthe rod I` in the direction X. X. A` slide 9 is displaceable along the dove-tail guide sudo i3 is provided with an annuiar body |.1

rotatable about. an axis U-U 'which lies in a plane containing the directions of displacement Y-Y and Z-Z' and is inclined at an angle ^/=20 to the direction of displacement Z-Z. The annular body I1 is rotatable relatively'to the slide I3 by means of a milled head I8 and. a worm gear I9, 20. A sup rt'2l issu-mounted in the annular body I1 as tobe rotatable about an axis V.-V intersecting the axis of rota-V tion U--U at right angles at a point M. The support 2| can be v rotated relatively to the annular body I1 by means of a screw 22 which is disposed in a bracket 23 of the body 2i `and pressed by means of a spring 25 against a plate 24 integral with the body l1. The housing 26 of a projection camera is so disposed on the support 2| as to be rotatable about an axis W-W intersecting the axis of rotation V-V at right angles at the point M. The objective 21 of the camera is mounted in the housing 26 in such a manner that its optical centre coincides with the point M and that its optical axis O-O and the axis of rotation W-W embrace an angle of 17. 28 is a glass plate which is fixed into the housing 26 and lies against the emulsion side of the image plate 29 to be projected. The glass plate 28 is so positioned in the housing 26 that its surface S-S coinciding with the emulsion side of the image plate 29 is at right angles to a straight line G-G lying in the plane determined by the optical axis 0-0 of the objective 21 and the axis of rotation W--W, and that its said surface includes an angle of 6 together with the axis O-O and an angle of 23 together with. the axis of rotation W-W. That surface of the glass plate 28 which coincides with the emulsion side S-S and is, accordingly, inclined at an angle =67 to the axis of rotation W-W bears two marks, namely a point` mark 30 coinciding with the point of intersection of the said surface and the straight line G-G, and a line mark 3| containing both the point mark 30 and the point of intersection of the axis O-O and the said surface, the purpose of the marks 30 and 8| being to facilitate adjusting the image plate 2l`in the camera. `A housing 32 placed on the housing 26 includes the illumination device, which consists of condenser lenses 33 and an incandescent bulb 84. P--P designates a plane which is parallel to the directions of displacement X-X and Z-Z and is indicative of a. medial position of the projection surface. When the image plate 28 has been exposed, for instance, at 43 to the horizontal plane, and assumes the position shown in the drawing, the plane P-P makes together withv the emulsion side S--S of the image plate the .said angle =43 and contains the line in which the emulsion `side S-S and the principal plane H-H of the objective 21 intersect each other at an angle of 6 on account of the described reciprocal positions of the objective 21 vand the surface bearing the marks 30 and 3l. The planes H-H, S--S and P-P are, accordingly, so positioned relatively to each other as to fullll the Scheimpflug condition of sharp definition, the angles a, and y corresponding, as required, to the equation y=a+90.

The point at'which the axis of rotation W-W and the emulsion layer of the image plate 29 intersect each other, is near the margin of the image plate. This position facilitates the orientation of the image plate 29 as compared to the usual position, in which the axis of rotation W-W coincides with the axis O-O or the said straight line G-G.

I claim:

A bearing for a camera.projecting an image on a plane of projection (P-P) in apparatus for photogrammetrically plotting image plates exposed on aircraft obliquely at adenite angle (a) to the horizontal plane, the camera containing an image plate, an objective and an illumination system disposed behind the image plate, the objective being so positioned relatively to the image plate that the principal plane (HH) of the objective passes through the line in which the emulsion side (S-S) of the image plate intersects the said projection plane (P-P) at a medial distance of this plane (P-P) from the objective, a three-dimensional system of cross slides supporting the camera, a bearing body mounted on this system of cross slides by means of a Cardan link, thecamera being so mounted on the bearing body that it is rotatable about an axis (IW-W) containing the optical centre (M) of the camera objective, that this optical centre (M) coincides with the centre of the Cardan link, andv that the axis of rotation (W-W) of the camera intersects at right angles the interior Cardan axis (VV) of the Cardan link, the image plate being inclined to the axis of rotation (W-W) of the cameraat such an angle that this plate is intersected by the axis of rotation (W-W) at a point lying as near the plate plumb line as possible, land the exterior Cardan axis (U-U) of the Cardan link being inclined to the said projection surface (P-P) at an angle ('y) equal to the sum of the said two angles (a and less O'I'IO v. GRUBER. 

